The present invention relates to a device for aerating water, especially during purification of water and for waste water. The device includes a rigid, essentially planar support member, and a plate of elastomeric material, such as rubber or rubber-like synthetic material. The plate is disposed on the support member and is provided with fine slits for the release of air. The support member is provided on its underside, remote from the plate, with one or more connectors for supplying air between the support member and the plate. The rim of the plate is pressed in an airtight manner from above against the support member by a profiled annular frame that is secured via screws or the like to the support member. The operational portions of the device are adapted to be disposed essentially horizontally in the water.
It is an object of the present invention to achieve a good, durable pressing of the plate against the support member, and hence an absolutely airtight connection, with little use of material.